Portable spot welder



g- 8, 1950 R. M. GASTON 2,517,653

PORTABLE SPOT WELDER Filed May a, 1949 4 Sheets-Sheet l I l W Aug. 8, 1950 R. M. GASTON PORTABLE SPOT WELDER 4 Sheets-Sheet 3 Filed May 3, 1949 FAxED CENTER Ryan/Z507, flaw; m mm 8, 1950v R. M. GASTON 2,517,653

PORTABLE SPOT WELDER Filed May 3, 1949 4 Sheets-Sheet 4 Patented Aug. 8, 1950 UNITED STATES ATENT OFFICET PORTABLE SPOT WELDER Ralph M. Gaston, Chicago, IlL, assignor, by mesne assignments, to Karma Manufacturing Company, Harvey, Ill, a corporation of Illinois Application May 3, 1949, Serial No. 91,097

12 Claims.

This invention relates, generally, to spot welders, and it has particular relation to portable spot welders which can be used in garages and auto mobile body repair shops for welding the thin sheet steel of automobile bodies and fenders.

However, the use of this invention is not so limited. It may be used to perform other welding operations as will be understood readily.

Among the objects of this invention are: To provide for moving a pair of welding electrodes of a spot Welder into and out of engagement with ii.

the work to be welded in a new and improved manner; to mount both electrodes for rocking movement and to rock them in the same direction at different speeds so that they move relatively toward or away from each other when one of them is moved; to interconnect the electrode mountings or holders so that, when one is rocked, its motion is translated into rocking movement of the other; to mount the electrode holders for rocking movement about individual axes which are spaced apart; to operate the electrode holders by means of levers attached thereto; to locate the axes of the electrode holders or levers and interconnect them in such manner as to multiply by several times the force applied to the levers so that the increased force is applied to the work between the welding electrodes; and to mount the levers on an assembly which includes a welding transformer that serves as a support for the two levers and also functions as one handle of a pair of handles, the other of which is an extension of one of the levers.

'Other objects of this invention will, in part, be obvious and in part appear hereinafter.

. This invention is disclosed in the embodiment thereof shown in the accompanying drawings and it comprises the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereinafter set forth and the scope of the application of which will be indicated in the appended claims.

For a more complete understanding of the nature and scope of this invention, reference can be had to the following detailed description taken together with the accompanying drawings, in which:

Figure 1 is a top plan view of a portable spot welder in which the present invention is incor porated;

Figure 2 is a view, in side elevation, of the spot welder shown in Figure l;

- Figure 3 is a view in front elevation of the spot .welder shown in Figure 2, the view showing the electrode holders in section;

Figure 4 is a view in rear elevation of the spot welder shown in Figure 2;

Figure 5 is a view, partly in side elevation and partly in longitudinal section, showing certain of the details of construction;

Figure 6 is a detail sectional view taken along the line 6--6 of Figure 3;

Figure '7 is a detail sectional view taken along the line 1-! of Figure 6;

Figures 8 and 9 are enlarged views of the electrode holders and portions of the levers in different operating positions; and

Figures 10, 11, 12, and 13 are perspective views of the levers and electrode holders and one of the end frames on which they are mounted.

Referring now particularly to Figures 1, 2 and 5 of the drawings, it will be observed that the reference character It designates, generally, a portable spot welder which includes a transformer that is indicated, generally, at I I. The transformer H includes end frames l2 and I3 with a stack Id of laminations therebetween. Suitable bolts 15 extend through the stack 14 of laminations between the end frames l2 and I3 for holding them in assembled relation. The transformer ii includes a single turn secondary winding the ends of which are indicated at IE and I7. Also it includes a primary winding having a number of turns corresponding to the voltage used and the ends of the primary winding are indicated at i8 and [9.

As illustrated in Figure 5 the end l8 of the primary winding is connected to a switch that is indicated, generally, at and is located in a boxlike extension 2| which is formed integrally with the end frame l2. The switch 20 is connected by a conductor 22 to a suitable source of current. It will be observed that the conductor 22 and the end of the primary winding is extend into a three conductor cable 23 which, it will be understood, is arranged to be connected to a suitable current source and to ground. A third conductor 21% is provided for grounding the spot welder I0 in order to avoid the application of any high voltage to the operator. The switch 20 includes an arm 25 which is biased to the switch open position by a coil compression spring 26. The switch may be closed by a pin 21 which is actuated by a trigger 28. It will be noted that the trigger 28 is pivotally mounted at 29 on an extension 30 that is formed integrally with the end frame l2. The trigger 28 is located underneath extending section 33 formed integrally therewith. The section 33 includes a pair of spaced arms 34 on the outer sides of which are oppositely disposed pairs of offset bearing surfaces 35 and 35. It will be noted that the bearing surfaces 35 are spaced nearer together than are the bearing surfaces 36 and that this provides the offset relationship just referred to. Alsoit will be noted that shafts 31 and 38 extend transversely through the pairs of bearing surfaces 35 and 36 respectively.

The shaft 31 is arranged to carry a generally O-shaped lever that is indicated, generally, at M in Figure 2 of the drawings. The O-shaped lever 4| includes a U-shaped lever, Figure 12, which is indicated, generally, at E2. It has openings 43 in its upstanding sides 44 for receiving the ends of the shaft 31. At its lower central portion the U- shaped lever 42 is provided with an integrally formed socket 45w'hich is longitudinally split at 56 and has a transversely extending clamp screw 41. for securing a. vrodlike electrode holder 48 therein. At its outer end the electrode holder 58 carries a transversely. extending electrode 49 which may be held inposition by a set screw 55 at the outer end of the electrode holder 48.

. The O-shaped lever it! also includes a handle membe that is indicated, generally, at in Figure of thedrawings. The handle member 5| may be secured by bolts 52, Figure 2, to the U-shaped lever 52. It will be understood that :the bolts 52 are threaded into tapped holes 53 in the upper ends of the sides 44 of the U-shaped lever 42. The handle member 5| has a rearwardly extending arm 55 that projects over the transformer H and is generally parallel to the hand hold 3|. It will be understood that the operator grips the arm 54 and the hand hold 31 with one hand andat the same time one of his fingers encircles the trigger 25 to operate the switch 20 for completing a circuit for energizing the primary winding of the transformer ll. Brackets 55 extend upwardly n opposite sides of the handle member 5|, as shown in Figure 10,

and they may be secured thereto by screws 56. A handle 51, preferably of wood, extends between the brackets 55 and is arranged to be gripped by the other hand of the operator. In this manfiner. he can manipulate the spot welder H] as may be desired.

. The shaft 33, which it will be recalled extends through the bearing surfaces35 on the outer sides of the arms .34, carries a generally C-shaped lever that is indicated, generally, at .59 i Figures 2 and 11 of the drawings. The generally c-shaped lever 59 has sides 66 which extend over the bearing surfaces 36 and which have openings 5| for receiving the ends of the shaft 38. The lever 59 carries a socket 62 which is split, at 63 and has a clamp screw 64 for securing an electrode holder -65 therein. The electrode holder 65 may be similar to the electrode holder 48-andit may carry an electrode 65 at its outer end which may be held place by a set screw 61. i It will be understood that thesocket 6.2 is formed separately from the generally C-shaped lever 59 although it is carried thereby. It is insulated therefrom by aplate 660i insulation that is illustrated in Figure 5. Suitable bolts 69 extend through the upper :central portion of the C-shaped lever 59 and into'the socket 62 for holding the same in position thereon. The bolts 69 are insulated from'I-the' c shaped lever 59 by suitable insulating washers '19. r

The socket 62 connected to the. .end 16 of the secondary winding by a flexible conductor 'H which may be made up of a number of thin and flexible plates of copper. The conductor H is generally U-shaped, as shown, and one end is positioned underneath the rear portion of 12 of the socket 62 and is clamped thereto by the set of bolts 55 which extend through a clamp plate 13. The other end of the flexible conductor H is connected to the end [6 of the secondary winding by bolts M which extend through a top flange 15 of the laterally extending section 33. The bolts i l are insulated from the flange 15 [by suitable insulating washers i5 and they extend into a plate H for clamping the rear end of the flexible conductor H to the end of iii of the secondary winding.

A similar arrangement, without the insulation, is provided for connecting the socket 45 to the other end ll of the secondary winding. It will be observed that a flexible conductor 85, similar to the conductor H, is provided and that the forward end f it is secured by bolts 8! to the socket 55. The bolts Bl extend through the socket 55 and into a clamp plate 82 for clamping the front end of the flexible conductor 85 therebetween. The rear end of the flexible conductor 85 is clamped by bolts 83 which extend through a bottom flange 3d of the laterally extending section 33 into a clamp plate 85. In accordance with this invention, provision is made for translating the movement of the generally O-shaped lever 4| to the generally .c-shaped lever 59 in suchmanner that the electrode tit moves fasterthan the electrode 56 so that, while they both move in the same direction, the former is brought into engagement with the work piece 95, Figure 9, while the electrode 56 is brought into engagement with the work piece 9 i. For this purpose knobs or detents, shown generally at 86 in Figure .7, are provided. Each knob or detent 86 includes a threaded section 8? which, as shown, is screwed into the corresponding sideM of the U-shaped lever 42. Also each knob-or detent 86 includes a cylindrical head 83 which projects into a U- shaped slot 39 at the end of each of the sides 50 of the C-shaped lever 59.

While the flexible conductors H and may possess suflicient resiliency to bias the electrode holders 48 and 55 apart, it may be desirable to provide springs 93, Figures 1 and 2 of the drawings, to provide additional biasing force. As here shown, it will be noted that the springs 93 are interposed between the rear portions of the sides 54 of the U-shaped lever 42 and the forward sur--- face of the end frame I3. It will be understood that the springs 93 may be located otherwise, .for example, between thev arm 55 and the hand hold 3! if desired.

Also it will be understood that different form of electrode holder 53 and 55 can be used. These electrode holders can be provided with openings extending longitudinally from their outer ends for receiving various types of electrode extensions as may be desired. Also different lengths of electrode holders 48 and (55 can be employed as may be desired.

In describing the operation of the portable spot welder i5 disclosed herein, it will be assumed first that the electrode holders 58 and 55 are positioned so that the electrodes 59 and 56 are spaced apart as illustrated in Figure 8 of the drawings. .Now the arm 54 is moved toward the handle 31' so that, as shown in Figure 9 of the drawings, the U- shaped lever E2 is swungfrom the position shown by the broken lines toitsposition shown by the full lines while the C-shaped lever 59 is moved from its position indicated by the broken lines to its position shown by the full lines. It will be recalled that the U-shaped lever 12, which forms a part of the O-shaped lever 4|, pivots about the shaft 31 as an axis while the C-shaped lever 59 pivots about the shaft 38 as an axis. Now these levers are interconnected through the knobs or detents 86 and particularly by the engagement of the heads 88 with one side of each of the slots 89. The length of the work arm for the lever 42 is the distance between the center of the shaft 31 and the center of the cylindrical head 88. This distance is less, one half as shown in the drawing, than the length of the power arm for the lever 59 which is the distance between the center of the shaft 38 and the cylindrical head 88. Thus, as illustrated in Figure 9, for a given movement of the U-shaped lever 42, the C-shaped lever 59 moves only through one half the same distance and, while the electrodes 88 and 48 both are i moved in the same direction, since the latter moves at twice the speed that the former does, they are caused to engage the work pieces 96 and SI as illustrated. Also because of the particular lever ratios involved, it is possible to exert a relatively great force between the electrodes 49 and 66 which, of course, is transmitted to the work pieces 90 and Si. In the particular embodiment of the invention illustrated there is a one to six lever ratio. That is, with a fifty pound force applied to the arm 54 a pressure of three hundred pounds is exerted between the electrodes 49 and 66.

When the work pieces to and 9! have been gripped as described, the operator depresses the trigger 28 to close the switch 20. and complete the circuit for energizing the primary winding of the welding transformer ii. In the particular construction disclosed, it is possible to obtain a welding current of the order of 2500 amperes. This has been found sufiicient to perform satisfactory welding operations on relatively light gauge metal.

Since certain further changes can be made in the foregoing construction and different embodiments of the invention can be made without departing from the spirit and scope thereof, it is intended that all matter shown in the accompanying drawings and described hereinhefore shall be interpreted as illustrative and not in a limiting sense.

What is claimed as new is:

1. In a manually operable spot welder, in combination, a support member having a laterally extending section provided with offset bearing faces, a pair of electrode holders adapted to carry welding electrodes to engage work to be welded, levers carrying said electrode holders and independently pivoted on said offset bearing faces, and detent means interconnecting said levers whereby when one is rocked about its pivot in one direction the other is rocked about its pivot in the same direction but through a diiferent angular extent to effeet movement of said welding electrodes toward or away from each other depending on the direction of movement.

2. In a manually operable spot welder, in combination, a support member having a laterally extending section provided with offset bearing faces, a pair of electrode holders adapted to carry welding electrodes to engage work to be welded, levers carrying said electrode holders and independently pivoted on said offset bearing faces, a knob on one of said levers, and a cooperating socket on the other of said levers whereby when one is rocked about its pivot in one direction the other is rocked about its pivot in the same direction but through a different angular extent to effect movement of said welding electrodes toward or away from each other depending on the direction of movement.

3. In a manually operable spot welder, in combination, a support member having a laterally extending. section provided with oppositely disposed pairs of effect bearing faces on opposite sides, a pair of electrode holders adapted to carry welding electrodes to engage work to be welded, levers carrying said electrode holders and independently pivoted on each pair of oppositely disposed bearing faces, and detent means on opposite sides of said section interconnecting said levers whereby when one is rocked about its pivot in one direction the other is rocked about its pivot in the same direction but through a different angular extent to effect movement of said welding electrodes toward or away from pending on the direction of movement.

4. In a manually operable spot welder, in combination, a support member having a laterally extending section provided with oppositely disposed pairs of offset bearing faces on opposite sides, a pair of electrode holders adapted to carry welding electrodes to engage work to be welded, levers carrying said electrode holders and independently pivoted on each pair of oppositely disposed bearing faces, knobs on one of said levers on opposite sides of said section, and cooperating sockets on the other of said levers whereby when one is rocked about its pivot in one direction the other is rocked about its pivot in the same direction but through a diiferent angular extent to effect movement of said welding electrodes toward or away from each other depending on the direction of movement.

5. In a manually operable spot welder, in combination, a support member having a laterally extending section provided with oppositely disposed pairs of offset bearing faces on opposite sides, a pair of electrode holders adapted to carry welding electrodes to engage work to be welded, levers carrying said electrode holders, one lever being generally O-shaped and pivoted on the inner pair of oppositely disposed bearing faces, the other lever being generally C-shaped and pivoted on the outer pair of oppositely disposed bearing. of said levers on opposite.

faces, knobs on one sides of said section, and cooperating sockets on the other of said levers whereby when one is rocked about its pivot in one direction the other is rocked about its pivot in the same direction but through a dilferent angular extent to effect movement of said welding electrodes toward or away from each other depending on the direction of movement.

6. The invention, as set forth in claim 5, wherein the knobs project outwardly from the O-shaped lever and the cooperating sockets are located in the ends of the arms of the C-shaped lever.

7. In a manually operable spot welder, in combination, a support member, a pair of electrode holders adapted to carry welding electrodes to engage work to be welded, levers carrying said electrode holders and independently pivoted on said support member, and detent means interconnecting said levers whereby when one isrocked about its pivot in one direction the other is rocked about its pivot in the same direction but through a different angular extent to effect movement of said welding electrodes toward or away from each other deeach other depending on the direction of movement..

8, In a manually operablespot welder, in combination, a support member, a pair of electrode.

levers, and a cooperating slotted socket on the other of'said levers whereby when one is rocked about it's pivot in one direction the other is rocked about its pivot in thesame direction but through a difierent angular extent to effect movement of said welding electrodes toward or away from each other depending on thedirection of movement.

9; In a manually operable spot welder, in combination; a transformer including a stack of laminations, primary and secondary windings thereon, and a frame at each end of said stack; a handle carried by one end frame and-extending longitudinally of said transformer, a laterally extending section carried by theother end frame; a pair'of electrode holders adapted to carry welding electrodes to engage work to be welded and con-- nected-to be energized from said secondary winding, levers carrying said electrode holders and independently pivoted on said section, detent means interconnecting said levers, and a handle extending from one of said levers along the first mentioned handle whereby when said handles 1: are'moved toward each other said welding electrodes are moved toward each other and vice versa.

10. In a manually operable spot welder, in combination; a transformer including a stack of laminations; primary and secondary windings thereon; and a frame at each end of said stack; a handle carried by one end frame and extending longitudinally of said transformer, a laterally extending section carried by the other end frame, a pair of electrode holders adapted to carry welding electrodes to engage work to be welded, flexible connections between said electrode holders and said secondary winding, levers carryingsaid-electrode holders and independently pivoted onsaid section, detent means interconnecting said levers, and a handle extending from one of said levers along the first mentioned handle whereby when said handles are moved toward each other said welding electrodes are moved toward each other and vice versa.

111.111 a manually operablespottwelder, in. coma. bination; a transformer including a stack; of:

laminations, primary and secondary windings thereon, and a frame at each end of said stack; a handle carriedby one end frame and extend ing longitudinally of said transformer, a laterally.

extending sectioncarried by the other end frame,

a pair of electrode holders adapted tocarry weldmeans interconnecting said levers, a handle extending from one of. said levers along the first. mentionedhandle whereby when saidhandles-are moved toward each other said welding electrodes are moved toward each other and vice versa,and-ahand grip on the second mentioned handle'which: may be gripped by one hand of an operator while his other hand grips said handles.

12. In a manually operable spot welder, in com-- bination; a transformer including a stack of laminations, primary and secondary windings thereon, and a frame at each end of said stack;

a handle carried by one end frame and extend ing longitudinally of said transformer, a laterally extending section carried by theother end frame, apair of electrode holders adapted tocarry welding electrodes to engage work to-be weldedand connected to be energized fromsaid secondary winding, levers carrying said electrodehol'ders and independently pivoted on said' sec-- tion, detent means interconnecting said levers, ahandle extending from one of said levers alongthe first mentioned handle whereby when said handles are moved toward each-other said-weld ing electrodes are moved toward each other and-- vice versa, and spring means cooperating withone of said levers and acting to bias said welding: electrodes apart.

RALPH M. GASTON.

REFEEEPJCES CITED;

The following references are of record in the file of this patent:

UNITED STATES, rATENrs.

Number Name Date 2,190,692 Bitter et a1. Feb; 20', 1940* 2,267,297 Campbell Dec; 23, 1941 

